High speed pass through test system and test method for electronic modules

ABSTRACT

A pass through test system for testing an electronic module includes an interface board, and metal fret test contactors configured to electrically engage terminal contacts on the module. The test contactors and interface board are mounted to an automated or manual pass through test handler configured to allow electrical engagement of the module with a zero insertion force. The interface board includes interface contacts configured to engage the test contactors at intermediate points along their lengths, and to shorten the electrical paths through the test contactors. The interface contacts are in electrical communication with high speed conductors on the interface board, and can be constructed of a conductive polymer material, or alternately as metal frets. During a test method the module is supported edge to edge and generally parallel to the interface board. In an alternate embodiment the test contactors are metal frets configured to simultaneously electrically engage the terminal contacts on the module and planar interface contacts on the interface board. The test method includes the steps of: providing the movable test contactors, electrically engaging the terminal contacts on the module and the interface contacts on the interface board using the test contactors, and then applying test signals through the test contactors and the terminal contacts to the modules.

FIELD OF THE INVENTION

[0001] This invention relates generally to the testing of electronicmodules, and more particularly to a high speed pass through test systemand test method for testing electronic modules.

BACKGROUND OF THE INVENTION

[0002] Electronic modules, such as semiconductor memory modules, multichip modules, semiconductor carriers, semiconductor packages, andmicroprocessors are routinely tested during manufacture. The modulesinclude terminal contacts in electrical communication with theelectronic devices contained on the modules. For performing various testprocedures on the modules, temporary electrical connections are made tothe terminal contacts.

[0003] One type of prior art electronic module 10, which is illustratedin FIGS. 1A and 1B, includes a substrate 12, and multiple semiconductorpackages 16 mounted to the substrate 12. The module 10 also includes arow of terminal contacts 14 on the substrate 12 in electricalcommunication with the integrated circuits contained on thesemiconductor packages 16. The terminal contacts 14 comprise generallyplanar, in-line metal pads located on opposing sides of the substrate 12along a lateral edge 18 thereof. The substrate 12 typically comprises anelectrically insulating material such as a glass filled plastic (FR-4),or a ceramic. In addition, the substrate 12 includes through openings 19which facilitate indexing and handling by automated test equipment andcarriers.

[0004] For testing the electronic module 10, test systems have beendeveloped and are commercially available from various manufacturers.These test systems are configured to make temporary electricalconnections with the terminal contacts 14 on the module 10. In addition,the test systems are configured to apply test signals through theterminal contacts 14 to the electronic devices on the module 10, andthen to analyze the response signals from the electronic devices. Oftentimes these test systems merely test the gross functionality of themodule 10, as the semiconductor packages 16 on the module 10 have beenpreviously individually tested and burned-in.

[0005] The test systems typically include test boards and test circuitryin electrical communication with the test boards. In addition, the testboards typically include interface boards having test contactorsconfigured to physically and electrically engage the terminal contacts14 on either side of the module 10. In general, there are two types oftest systems, which are sometimes referred to as “pass through testsystems”, or “socket test systems”.

[0006]FIG. 1C illustrates a pass through test system 11PT having aninterface board 13PT, and test contactors 15PT on the interface board13PT. The test contactors 15PT are in electrical communication with testcircuitry (not shown). In addition, the test contactors 15PT are movablefrom an inactive (open) position in which the terminal contacts 14 onthe module 10 are not engaged, to an active (closed) position in whichthe terminal contacts 14 on the module 10 are physically andelectrically engaged.

[0007] As shown in FIG. 1C, with the test contactors 15PT in an inactive(open) position, the module 10 can be indexed into a contactor areabetween the test contactors 15PT, as indicated by arrow 17PT. With themodule 10 located in the contactor area, the test contactors 15PT can bemechanically moved to the active (closed) position to physically andelectrically engage the terminal contacts 14. The pass through testcontactors 15PT are sometimes referred to as being “zero insertionforce” (ZIF) contactors because temporary electrical connections can bemade without an insertion force being placed on the module 10.

[0008]FIG. 1D illustrates a socket test system 11S having an interfaceboard 13S, and test contactors 15S on the interface board 13S. In thiscase, the test contactors 15S are normally in an active (closed)position, but are mechanically moved to an inactive (open) position asthe module 10 is inserted from above, as indicated by arrow 17S. Whenthe module 10 is in place, the test contactors 15S move back to theactive (closed) position to physically and electrically engage theterminal contacts 10. The socket test contactors 15S are sometimesreferred to as being “low insertion force” (LIF) contactors because aninsertion force is exerted on the module 10 in making the temporaryelectrical connections with the test contactors 15S.

[0009] One advantage of the pass through test system 11PT (FIG. 1C) overthe socket test system 11S, is that no insertion forces are exerted onthe module 10 to provide electrical engagement for testing. Accordingly,less physical stress is placed on the module 10 during testing with thepass through test system 11PT. Also, as the number of terminal contacts14 on the module 10 increases, the insertion forces exerted by thesocket test system 11S increase. The socket test system 11S cantherefore damage the module 10, or the terminal contacts 14 on themodule 10, and can be more expensive to operate and maintain.

[0010] The present invention is directed to an improved pass throughtest system. In pass through test systems it is desirable to maketemporary electrical connections with the terminal contacts 14 on themodules 10 that are reliable, and have low electrical resistance. Thisrequires that the terminal contacts 14 be scrubbed, or alternatelypenetrated by the test contactors 15PT, such that oxide layers andsurface contaminants on the terminal contacts 14 do not adversely affectthe temporary electrical connections. However, in scrubbing orpenetrating the terminal contacts 14, damage to the terminal contacts 14and modules 10 must be minimized.

[0011] It is also advantageous in pass through test systems for thetemporary electrical connections to provide electrical paths that areshort in length to facilitate the application of high speed testsignals, and to prevent capacitive coupling and the introduction ofnoise and spurious signals. Further, it is advantageous to make, andthen break, the temporary electrical connections as quickly as possible,to facilitate a high throughput for the test procedure.

[0012] The pass through test system of the invention includes testcontactors configured to make temporary electrical connections that arereliable, have low electrical resistance, and minimally damage terminalcontacts on the modules. In addition, the test contactors are relativelyinexpensive to make, provide a high throughput, and can be operated in aproduction environment with minimal maintenance.

SUMMARY OF THE INVENTION

[0013] In accordance with the present invention, a pass through testsystem and test method for testing electronic modules are provided. Inillustrative embodiments, the test system is configured for testingelectronic modules having planar, in-line terminal contactssubstantially as previously described.

[0014] The test system includes test circuitry configured to generatetest signals, and an interface board having interface contacts, and highspeed conductors, in electrical communication with the test circuitry.The interface board can be mounted to an automated or manual testhandler configured to transport, align, and hold the module on edge,generally parallel to the module.

[0015] The test system also includes test contactors configured toengage the terminal contacts on the component, and to simultaneouslyengage the interface contacts on the interface board. In illustrativeembodiments, the test contactors comprise fret contacts configured toengage the terminal contacts with a zero insertion force (ZIF) on themodule. An actuator mechanism moves the test contactors from an inactive(open) position wherein neither the terminal contacts on the module, northe interface contacts on the interface board are engaged, to an active(closed) position wherein both the terminal contacts and the interfacecontacts are electrically engaged.

[0016] During electrical engagement of the terminal contacts, theinterface contacts electrically engage the test contacts at anintermediate point along a length thereof, such that the electricalpaths through the test contactors to the high speed conductors on theinterface board are shortened. The interface contacts can compriseconductive polymer bumps, or alternately fret-type contacts. Inaddition, the high speed conductors on the interface board can have amulti level, or interleaved configuration to provide an increaseddensity and impedance adjustment.

[0017] The test method includes the steps of: providing an interfaceboard comprising a plurality of interface contacts and high speedconductors in electrical communication with test circuitry; providing aplurality of movable test contactors comprising fret contacts configuredto electrically engage the terminal contacts and the interface contactswith a zero insertion force on the module; placing the module edge toedge and generally parallel to the interface board; moving the testcontactors to electrically engage the terminal contacts on the moduleand the interface contacts on the interface board; and then applyingtest signals through the interface contacts, the test contactors and theterminal contacts to the module.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1A is a plan view of a prior art electronic module;

[0019]FIG. 1B is a side elevation view of FIG. 1A;

[0020]FIG. 1C is a schematic side elevation view of a prior art passthrough test system,

[0021]FIG. 1D is a schematic side elevation view of a prior art sockettest system;

[0022]FIG. 2A is a schematic side elevation view of a test systemconstructed in accordance with the invention illustrating testcontactors of the system prior to electrical engagement of terminalcontacts on a module under test;

[0023]FIG. 2B is a schematic cross sectional view of the test system ofFIG. 2A taken along line 2B-2B of FIG. 2A;

[0024]FIG. 2C is a schematic side elevation view of the test system ofFIG. 2A illustrating the test contactors during electrical engagement ofthe terminal contacts on the module under test;

[0025]FIG. 2D is a schematic cross sectional view of the test system ofFIG. 2A taken along line 2D-2D of FIG. 2C;

[0026]FIG. 2E is a partial side elevation view equivalent to FIG. 2C ofan alternate embodiment test system having fret-type interface contacts;

[0027]FIG. 3A is a schematic side elevation view of an alternateembodiment test system constructed in accordance with the inventionillustrating test contactors prior to electrical engagement of terminalcontacts on a module under test; and

[0028]FIG. 3B is a schematic side elevation view of the test system ofFIG. 3A illustrating the test contactors during electrical engagement ofthe terminal contacts on the module under test.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] As used herein, the term “pass through test system” means a testsystem in which temporary electrical connections are made with theterminal contacts 14 on the module 10 with a “zero insertion force”. Asused herein, the term “zero insertion force” means that no forces arebeing exerted on the module 10 to move the test contactors 24 in makingthe temporary electrical connections.

[0030] Referring to FIGS. 2A-2D, a pass through test system 20constructed in accordance with a first embodiment of the invention, andconfigured to test electronic modules 10, is illustrated. The testsystem 20 includes a plurality of test contactors 24 configured to maketemporary electrical connections with the terminal contacts 14 on themodule 10. In FIGS. 2A and 2B, the test contactors 24 are shown in aninactive (open) position wherein the terminal contacts 14 are notengaged. In FIGS. 2C and 2D, the test contactors 24 are shown in anactive (closed) position wherein the terminal contacts 14 areelectrically engaged.

[0031] The test contactors 24 can have a conventional fret-typeconfiguration, and can comprise a conventional low electricalresistivity material such as copper or a copper alloy such as berylliumcopper. The test contactors 24 can be etched, stamped, machined, orotherwise shaped in a desired configuration. In the illustrativeembodiments, the test contactors 24 include angled tip portions 36configured to penetrate and exert spring forces on the terminal contacts14.

[0032] In addition to the test contactors 24, the test system 20 alsoincludes an interface board 22, and interface contacts 26 on theinterface board 22. The interface contacts 26 are configured toelectrically engage the test contactors 24 at some intermediate pointalong their length, and to shorten the electrical paths from theterminal contacts 14 through the test contactors 24. The test system 20also includes test circuitry 28 configured to generate and apply highspeed test signals through the interface contacts 26 and the testcontactors 24, to the integrated circuits contained on the semiconductormodules 10, and to analyze the resultant signals.

[0033] The test contactors 24 and the interface board 22 are configuredfor mounting to an automated or manual pass through test handler 30. Thetest handler 30 is represented schematically by the block in FIGS. 2Aand 2C. Support, movement and indexing of the module 10 can be providedby the test handler 30. In addition, support of the interface board 22and the test contactors 24 can be provided by the test handler 30.Suitable automated pass through test handlers are commercially availablefrom Advantest Corporation, Tokyo, Japan, and Kinetrix, Inc. Bedford,N.H., as well as other manufacturers.

[0034] Actuator mechanisms 34 on the test handler 30, such as acylinders, cams or motors, produce and control movement of the testcontactors 24. Terminal ends 44 (FIG. 2A) of the test contactors 24 arein physical contact with the actuator mechanisms 34. However, theterminal ends 44 perform no electrical function, as the electrical pathsthrough the terminal contacts 44 are from the tip portions 36 thereof,through intermediate points 46 (FIG. 2C) in physical and electricalcontact with the interface contacts 26.

[0035] The interface board 22 comprises an electrically insulatingmaterial, such as molded plastic, a glass filled resin (e.g., FR-4) or aceramic. In addition to the interface contacts 24, the interface board22 also includes high speed conductors 32 in electrical communicationwith the interface contacts 24 and with the test circuitry 28. The highspeed conductors 32 are configured to transmit the high speed testsignals without generating parasitic inductance, capacitive coupling andcross talk.

[0036] The high speed conductors 32 can comprise conventional lowresistance conductive traces in a deposited configuration. For example,the high speed conductors 32 can comprise metal traces formed by anadditive process (e.g., deposition through a mask onto the interfaceboard 22) or a subtractive process (e.g., blanket deposition of a metallayer on the interface board 22 and etching).

[0037] As another alternative, the high speed conductors 32 can have alaminated construction, such as metal traces on a polymer film (e.g.,TAB tape). With a laminated construction, the high speed conductors 32can also have an interleaved, or strip line configuration, with some ofthe electrical paths, such as ground paths, contained on parallelplanes. Such an interleaved configuration would permit an impedance ofthe high speed conductors 32 to be adjusted as required.

[0038] In the illustrative embodiment, the interface contacts 26comprise conductive polymer bumps having a desired size and shape. Inaddition, the interface contacts 26 are illustrated as being generallysquare shaped bumps. However, this shape is merely illustrative, andother shapes such as domed, hemispherical, conical, pyramidal can alsobe used. Further, the interface contacts 26 can include angled surfacesconfigured to provide engagement surfaces that match the angle of thetest contactors 24 in the active (closed) position. Alternately, theinterface contacts 26 can include grooves, or slits, configured toretain the test contactors 24 in the active (closed) position. Theinterface contacts 26 can be deposited directly on terminal portions ofthe high speed conductors 32 using a suitable deposition process such asscreen printing or stenciling. Preferably a pattern of the interfacecontacts 26, and the terminal portions of the high speed conductors 32exactly matches a pattern of the test contactors 24.

[0039] A conductive polymer material for forming the interface contacts26 can include an elastomeric matrix material having conductiveparticles embedded therein. Further, the conductive particles can beconfigured to provide an isotropic (or alternately anisotropic)electrically conductive path between the test contactors 24 and the highspeed conductors 32. Besides providing conductive paths, the conductiveparticles can also function to penetrate into the test contactors 24,such that low resistance electrical connections are made.

[0040] Suitable elastomeric matrix materials for the conductive polymermaterial include epoxy, silicone, natural rubber, synthetic rubber, andsimilar elastomeric materials having suitable compressive and adhesivecharacteristics. Suitable materials for the conductive particles includesilver and carbon in flake or dendritic form. Also, the conductivepolymer material can comprise a conventional commercially availablecomposition. Suitable conductive polymers are commercially availablefrom various manufacturers including Shinetsu Chemical Co., Japan; EPITechnologies, Richardson Tex.; A.I. Technology, Trenton N.J.; andSheldahl, Northfield, Minn.

[0041] In the active (closed) position of the test contactors 24 shortelectrical paths are provided between the terminal contacts 14 on themodule 10 and the interface contacts 26 on the interface board 22.Because these electrical paths are relatively short, impedance, crosstalk, and capacitive coupling are reduced. In addition to the shortelectrical paths, the test contactors 24 provide several advantages forapplying test signals to the module 10. One advantage is that the tipportions 36 of the test contactors 24 penetrate the terminal contacts 14as the test contactors 24 are moved by the actuator mechanism 34 intothe closed position. This penetration helps to provide low resistancetemporary electrical connections. Another advantage is that the tipportions 36 of the test contactors 24 exert spring forces formaintaining the electrical connections. The actuator mechanism 34 canalso be configured to help exert and maintain these spring forces.

[0042] Still another advantage of the test contactors 24 is thattemporary electrical connections can be made for testing, and thenquickly disconnected following testing by the movement of the testcontactors 24. A high throughput, and a low dwell time, can thus beprovided for testing multiple modules 10 in a production environment. Inaddition, the test contactors 24 are relatively robust and are able towithstand abuse in a production environment. Still further, the testcontactors 24 make the temporary electrical connections with theterminal contacts 14 without an insertion force being exerted on themodule 10 (i.e., zero insertion force).

[0043] As shown in FIGS. 2A and 2C, in the illustrative embodiment, thetest handler 30 is configured to support the module 10 and the interfaceboard 22 in a parallel, edge to edge configuration. Specifically, themajor planar surfaces of the module 10 and the interface board 22 aregenerally parallel to a common plane 38. In addition, an edge 40 of themodule 10, and an edge 42 of the interface board 22, are aligned andproximate to one another. In the illustrative embodiment, the edges 40and 42 are shown as being spaced by a small distance. Preferably thisspacing distance is as small as possible, or can be entirely eliminated,to provide relatively short electrical paths (e.g., 0.25 inches or less)between the terminal contacts 14 and the interface contacts 26.

[0044] Also in the illustrative embodiment, some of the test contactors24 are configured to electrically engage every other terminal contact 14on a first side of the module 10, while others of the test contactors 24are configured to electrically engage every other terminal contact 14 onan opposing second side of the module 10. Also, the test contactors 24can be configured to electrically engage other types of terminalcontacts than the flat planar terminal contacts 14 shown in theillustrative embodiments. For example, the test contactors can beconfigured to electrically engage bumped contacts (e.g., solder balls ina ball grid array), pin contacts (e.g., pins in a pin grid array), andvarious lead type contacts (e.g., gull wing leads, j-bend leads).

[0045] Referring to FIG. 2E, an alternate embodiment test system 20B isillustrated. The test system 20B is substantially similar inconstruction to the previously described test system 20. However, thetest system 20B includes an interface board 22B having interfacecontacts 26B in the form of metal frets, or spring contacts, that aresubstantially similar in construction to the test contactors 24. In thealternate embodiment test system 20B, the interface contacts 26B takethe place of the previously described conductive polymer interfacecontacts 26. As such, the interface contacts 26B are in electricalengagement with the high speed conductors 32, and are configured toelectrically engage the test contactors 24.

[0046] Referring to FIGS. 3A and 3B, an alternate embodiment test system20A is illustrated. The test system 20A is substantially similar inconstruction to the previously described test system 20. However, thetest system 20B includes an interface board 22A having interfacecontacts 26A in the form of planar pads that are substantially similarin construction to the terminal contacts 14 on the module 10. In thealternate embodiment test system 20A, the interface contacts 26A takethe place of the previously described conductive polymer interfacecontacts 26. As such, the interface contacts 26A are in electricalcommunication with high speed conductors 32A on the interface board 22Aand external test circuitry 28A.

[0047] The test system 20A also includes test contactors 24A in the formof metal frets configured to simultaneously electrically engage theterminal contacts 14 on the component 10, and the interface contacts 26Aon the interface board 22A. The test contactors 24A are physicallyattached to an actuator mechanism 34A of a test handler 30A. Theactuator mechanism 34A is configured to move the test contactors 24Afrom the inactive (open) position of FIG. 3A, to the active (closed)position of FIG. 3B. In the active (closed) position of the testcontactors 24A relatively short electrical paths are provided betweenthe terminal contacts 14 on the module 10 and the interface contacts 26Aon the interface board 22A. Because these electrical paths arerelatively short, impedance, cross talk, and capacitive coupling arereduced.

[0048] The test contactors 24A have spring segment terminal portionsconfigured to exert spring forces on the terminal contacts 14 and on theinterface contacts 26A. In addition, the test contactors 24A areconfigured to exert clamping forces on either side of the module 10 andthe interface board 22A. These features help the test contactors 24A tomake reliable temporary electrical connections. Also the metal fretconstruction makes the test contactors 24A robust and able to withstandthe rigors of a production environment.

[0049] As with the previous embodiment, the test handler 30A isconfigured to index the module 10 into position for testing, and then tomove the module 10 out of the test handler 30A following testing. Inaddition, the test handler 30A is configured to support the module 10and the interface board 22A generally parallel to a common plane 38A.Also, the module 10 and the interface board 22A are oriented edge toedge, with an edge 40A of the module 10 spaced from and generallyparallel to an edge 42A of the interface board 22A.

[0050] Thus the invention provides a pass through test system and a passthrough test method for electronic modules. Although the invention hasbeen described with reference to certain preferred embodiments, as willbe apparent to those skilled in the art, certain changes andmodifications can be made without departing from the scope of theinvention, as defined by the following claims.

I claim:
 1. A system for testing an electronic module having a pluralityof terminal contacts comprising: a plurality of contactors movable froman inactive position to an active position and configured toelectrically engage the terminal contacts with a zero insertion force onthe module; and a board comprising a plurality contacts configured inthe second position of the contactors to electrically engage thecontactors at intermediate points thereon to shorten electrical pathsthrough the contactors.
 2. The system of claim 1 wherein the contactscomprise a conductive polymer material.
 3. The system of claim 1 whereinthe contactors comprise metal frets.
 4. The system of claim 1 whereinthe contactors comprise first metal frets and the contacts comprisesecond metal frets.
 5. The system of claim 1 further comprising aplurality of conductors on the board in electrical communication withtest circuitry.
 6. A system for testing an electronic module having aplurality of terminal contacts comprising: a test circuitry configuredto generate and apply test signals to the module; a plurality ofcontactors movable to electrically engage the terminal contacts with azero insertion force on the module to provide a plurality of separateelectrical paths to the test circuitry; and a board comprising aplurality of contacts in electrical communication with the testcircuitry, the contacts configured to electrically engage the contactorsat intermediate points thereon to shorten the electrical paths.
 7. Thesystem of claim 6 wherein the contacts comprise a conductive polymermaterial.
 8. The system of claim 6 wherein the contacts compriseconductive polymer bumps.
 9. The system of claim 6 wherein thecontactors comprise metal frets.
 10. The system of claim 6 wherein thecontactors comprise first metal frets and the contacts comprise secondmetal frets.
 11. The system of claim 6 wherein the module and the boardare oriented edge to edge generally parallel to a common plane.
 12. Asystem for testing an electronic module having a plurality of terminalcontacts comprising: a test circuitry configured to generate and applytest signals to the module; a board comprising a plurality of contactsand a plurality of conductors in electrical communication with the testcircuitry; and a plurality of contactors movably mounted proximate tothe board, the contactors comprising metal frets configured tosimultaneously electrically engage the terminal contacts and thecontacts to establish electrical communication there between with a zeroinsertion force on the module.
 13. The system of claim 12 wherein thecontacts comprise conductive polymer bumps.
 14. The system of claim 12wherein the contactors comprise first tip portions configured to exertspring forces on the terminal contacts and second tip portionsconfigured to exert spring forces on the terminal contacts.
 15. Thesystem of claim 12 further comprising a test handler configured tosupport the board and the module edge to edge and generally parallel toa common plane.
 16. The system of claim 12 wherein the module comprisesan element selected from the group consisting of semiconductor memorymodules, multi chip modules, semiconductor carriers, semiconductorpackages, and microprocessors.
 17. A system for testing an electronicmodule having a plurality of terminal contacts comprising: a testcircuitry configured to generate and apply test signals to the module; aplurality of contactors comprising metal frets movable from an inactiveposition to an active position to electrically engage the terminalcontacts; and a board comprising a plurality conductors in electricalcommunication with the test circuitry and a plurality of conductivepolymer bumps on the conductors configured to electrically engage thecontactors to shorten the electrical paths therethrough.
 18. The systemof claim 17 further comprising an actuator mechanism for moving thecontactors from the inactive position to the active position with a zeroinsertion force on the module.
 19. The system of claim 18 furthercomprising a test handler for supporting and indexing the module. 20.The system of claim 19 wherein the test handler supports the board andthe module edge to edge and generally parallel to a common plane. 21.The system of claim 20 wherein the contactors comprise tip portionsconfigured to penetrate and exert spring forces on the terminalcontacts.
 22. A system for testing an electronic module having aplurality of terminal contacts comprising: a test circuitry configuredto generate and apply test signals to the module; a plurality ofcontactors comprising metal frets movable from an inactive position toan active position to electrically engage the terminal contacts; and aboard comprising a plurality conductors in electrical communication withthe test circuitry and a plurality of second metal frets on theconductors configured to electrically engage the contactors to shortenthe electrical paths therethrough.
 23. The system of claim 22 furthercomprising an actuator mechanism for moving the contactors from theinactive position to the active position with a zero insertion force onthe module.
 24. The system of claim 23 further comprising a test handlerfor supporting and indexing the module.
 25. The system of claim 24wherein the test handler supports the board and the module edge to edgeand generally parallel to a common plane.
 26. The system of claim 25wherein the contactors comprise tip portions configured to penetrate andexert spring forces on the terminal contacts.
 27. The system of claim 26wherein the conductors have a multi level configuration.
 28. A methodfor testing an electronic module having a plurality of terminal contactscomprising: providing a board comprising a plurality of conductivepolymer contacts in electrical communication with test circuitry;providing a plurality of movable contactors comprising a plurality offret contacts configured to electrically engage the terminal contactsand the contacts; placing the module on the board with a zero insertionforce and the terminal contacts proximate to the test contactors; movingthe contactors to electrically engage the terminal contacts and thecontacts; and applying test signals through the contactors and theterminal contacts to the module.
 29. The method of claim 28 wherein thecontactors include tip portions configured to exert spring forces on theterminal contacts.
 30. The method of claim 28 wherein the contactorselectrically engage the contacts at intermediate points on thecontactors.
 31. A method for testing an electronic module having aplurality of terminal contacts comprising: providing a test circuitryconfigured to generate and apply test signals to the module; providing aplurality of contactors movable from an inactive position to an activeposition, the contactors configured to electrically engage the terminalcontacts with a zero insertion force on the module; providing a boardcomprising a plurality contacts in electrical communication with thetest circuitry configured in the second position of the contactors toelectrically engage the contactors at intermediate points thereon toshorten electrical paths through the contactors. moving the contactorsto electrically engage the terminal contacts and the contacts; andapplying test signals through the contactors and the terminal contactsto the module.
 32. The method of claim 31 wherein the contacts comprisea conductive polymer.
 33. The method of claim 31 wherein the contactorscomprise fret contacts.
 34. The method of claim 31 wherein the contactscomprise second fret contacts.
 35. The method of claim 31 wherein thecontactors comprise first fret contacts and the contacts comprise secondfret contacts.
 36. A method for testing an electronic module having aplurality of terminal contacts comprising: providing a board comprisinga plurality of contacts and conductors in electrical communication withtest circuitry; providing a plurality of movable contactors comprisingfret contacts configured to electrically engage the terminal contactsand the contacts with a zero insertion force on the module; placing themodule and the board edge to edge and generally parallel to a commonplane; moving the contactors to electrically engage the terminalcontacts on the module and the contacts on the board; and applying testsignals through the contacts, the contactors and the terminal contactsto the module.
 37. The method of claim 36 wherein the contactorscomprise first tip portions configured to electrically engage theterminal contacts and second tip portions configured to electricallyengage the contacts.
 38. The method of claim 36 wherein the contactscomprise conductive polymer bumps.
 39. The method of claim 36 whereinthe contacts comprise conductive polymer bumps on the conductors. 40.The method of claim 36 wherein the conductors have a multi levelconfiguration.
 41. The method of claim 36 wherein the module comprisesan element selected from the group consisting of semiconductor memorymodules, multi chip modules, semiconductor carriers, semiconductorpackages, and microprocessors.
 42. A method for testing an electronicmodule having a plurality of terminal contacts comprising: providing aplurality of movable contactors comprising fret contacts configured toelectrically engage the terminal contacts with a zero insertion force onthe module; providing a board comprising a plurality of conductors andconductive polymer contacts in electrical communication with testcircuitry and configured to electrically engage the contacts atintermediate points on the contactors; placing the module and the boardgenerally parallel to a common plane; moving the contactors tosimultaneously electrically engage the terminal contacts on the moduleand the conductive polymer contacts on the board; and applying testsignals through the conductors, the conductive polymer contacts, thecontactors and the terminal contacts to the module.
 43. The method ofclaim 42 wherein the conductive polymer bumps are on the conductors. 44.The method of claim 42 wherein the conductors have a multi levelconfiguration.
 45. The method of claim 42 wherein the module comprisesan element selected from the group consisting of semiconductor memorymodules, multi chip modules, semiconductor carriers, semiconductorpackages, and microprocessors.
 46. The method of claim 42 wherein duringthe placing step the module and the board are oriented edge to edge. 47.The method of claim 42 wherein during the placing step the module andthe board are oriented edge to edge and spaced from one another.
 48. Apass through test contactor for testing an electronic module having aterminal contact comprising: a fret contact configured to establish atemporary electrical connection with the terminal contact with a zeroinsertion force on the module, the fret contact comprising a firstportion configured to electrically engage the terminal contact, a secondportion in physical contact with an actuator mechanism configured tomove the fret contact, and a intermediate portion between the firstportion and the second portion configured to electrically engage acontact a board.
 49. The contactor of claim 48 wherein the contact onthe board comprises a conductive polymer.
 50. The contactor of claim 48wherein the contact on the board comprise a second fret contact.
 51. Thecontactor of claim 48 wherein the first portion comprises a spring tip.52. In a pass through test system including test circuitry for applyingtest signals to an electronic module having a terminal contact, a testcontactor for establishing electrical communication between the testcircuitry and the module comprising: a board comprising a contact inelectrical communication with the test circuitry; and a fret contactmovable from an inactive position to an active position, the fretcontacts comprising a tip portion configured to electrically engage theterminal contact with a zero insertion force on the module, and anintermediate portion configured to electrically engage the contact. 53.The contactor of claim 52 further comprising a terminal portionconfigured for connection to an actuator mechanism.
 54. The contactor ofclaim 52 wherein the fret contact comprises etched, stamped or machinedcopper.